The research proposed is concerned with the synthesis and reactions of 1-aryl-2,3,3-trialkyldiaziridines, 1,1-dialkyl-1-H-diazirino(1,2-b) phthalazine-3,8-diones and bicyclic diaziridines. We have shown that the 1,1-dialkyl-1H-diazirino (1,2-b) phthalazine-3,8-diones are effective alkylating reagents for nitrones and enamines and these alkylation reactions are being studied and extended. Emphasis is also placed on the ability of 1-aryl-2,3,3-trialkyldiaziridines and 1,1-dialkyl-1-H-diazirino (1,2-b) phthalazine-3,8-diones to form 1,3-dipoles and for these 1,3-dipoles to undergo cycloaddition reactions with 1,3-dipolarophiles. Both the alkylation reactions and the cycloaddition reactions described in this proposal represent new and general synthetic routes to rather inaccessible heterocyclic systems. Synthetic routes to novel bicyclic diaziridines will be explored and the chemistry of these compounds investigated. Save for one investigation the diaziridines have not been studied as biological alkylating reagents. Our work with the 1,1-dialkyl-1-H-diazirino (1,2-b) phthalazine-3,8-diones indicate that they are alkylating reagents and should be tested for their biological activity. Relatively little is known about the chemistry of diaziridines. The studies detailed in this proposal goes a long way in showing the versatility of these compounds as precursors to many heterocyclic systems.